New findings suggest a chemical in marijuana can prevent some people from going blind.
Retinitis pigmentosa is a genetic eye disease that leads to severe vision loss and blindness. The disease affects 1 in 4,000 people and worsens as cells in the retina, called photoreceptors, die off.
But a study published this month in Experimental Eye Research shows chemicals in marijuana, known as cannabinoids, may be able to slow this down.
Using a synthetic form of THC, the compound responsible for marijuana’s high, researchers at the University of Alicante in Spain were able to prevent vision loss in rats with the disorder.
“These data suggest that cannabinoids are potentially useful to delay retinal degeneration in retinitis pigmentosa patients,” wrote Dr. Nicolás Cuenca, the study’s lead author.
At the end of 90 days, rats that received treatment performed better on vision tests and had 40% more photoreceptors than untreated rats. THC also seemed to protect a number of other eye structures, including inner layers of the retina.
Although encouraging, the results were not much of a surprise. As the team notes, cannabinoids have shown promise in treating a variety of degenerative disorders, ranging from Parkinson’s and Alzheimer’s to diabetes and stroke.
Marijuana has also been reported to help in other eye diseases like glaucoma.
In fact, studies show marijuana pathways exist in different parts of the eye. And as early as the 70s, scientists observed a number of interesting effects of marijuana on vision.
For example, a study published in 1978 found marijuana caused a delay in pupil adjustment, concluding that it “seems likely that marijuana or a metabolic product of marijuana acts directly on the retina to produce the delay in glare recovery.”
While the latest study did not look at the mechanisms underlying the benefits of cannabinoids in retinitis pigmentosa, the authors conclude that further research should be carried out.